To better understand the contribution of cerebral capillary endothelial cells (EC) to vascular function, we will examine some of their in vitro morphological, pharmacological and immunological properties. This project has four major objectives: a) to establish primary EC cultures and a cell line of EC from rat cerebral cortical microvessels, and prepare monoclonal antibodies (by the lymphocyte hybridoma technique) to their surface components for use as EC-specific surface markers, and for use in sorting (fluorescence activated cell sorting) EC from mixed cell preparations to produce pure short-term and long-term cultures of EC; b) to delineate the alpha- and beta-adrenergic, and GABA receptor activities which these cells may possess, test the effects of chronic and acute application of mono-specific antisera on morphological, enzymatic and receptor properties used in establishing the identity of these cultured cells; c) to establish co-cultures of EC with astro-glial and smooth muscle cells in order to identify and re-evaluate the nature and cause of any changes observed in the morphological, receptor and immunological properties (as set out above) in EC compared with EC-only cultures; d) as a long range goal, during the fourth year we shall begin similar comparative in vitro studies with EC obtained from stroke-prone, spontaneously hypertensive rats (SP-SHR), in an effort to identify differences from EC of normotensive animals. Such observations may lead to a better understanding of the possible contribution of EC to pathology of the cerebral microvasculature caused by chronic hypertension.